[SATLUG] Attn: Bob Tracy

[David Kowis]

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Bob Tracy wrote:
> On Wed, 10 Jan 2007 11:47:18 -0600, David Kowis wrote
>> I'm going to take this opportunity to point out that a statistical
>> filter won't have this problem.
> 
> Acknowledged, but the problem that *all* statistical filters have is
> they must receive the message before they can analyze it.  My position
> to date has been that once the DATA command in an SMTP transaction has
> been issued, the battle with a spammer is lost.  Folks who have plenty
> of horsepower to throw at the problem don't mind (for the most part)
> the loss of available computing power due to message content analysis.
> Envelope filtering, while admittedly imperfect, allows me to use an
> AMD K6-III/450 system without having to suffer the compute burden of
> analyzing 2,000+ messages/day (and that's for a single user).

I wish could give you a total of the messages I receive in a day. I
don't doubt that it could be upwards of the 1000 mark. My mailserver is
a P3 500, so the performance hit isn't going to slow down your server :)

Unfortunately the way to win the war on spam is to prevent anyone from
seeing the mail. Rejection based on envelopes is ideal, but you don't
have a good enough method of ensuring that what is in that envelope is
garbage.

> 
> The single most effective spam filter I've seen in terms of maximal
> results for minimal effort is enabling Postfix's "reject_unknown_client"
> feature.  On a typical day, this one filter alone accounts for half the
> total of spam I don't see.

I think I've got that on as well, it doesn't stop it all, but does
discard lots of mails from bogus domain names. I should probably turn it
off to avoid robbing my statistical filter of data.

David
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